Labour have held the seat of Feltham and Heston in a by-election after the death of their MP Alan Keen last month.
Labour polled 12,639 votes, and the Tories polled 6,436, meaning Labour extended its majority on the general election by nearly 2,000 votes to 6,203.
Perhaps the most interesting numbers of the night were between the Lib Dems, who polled just over 1,300 votes and UKIP, which polled just over 1,200. This is a fairly accurate translation of recent opinion polls, which have put the two parties neck-and-neck.
Labour's winning candidate and the newest MP in Parliament, Seema Malthotra, said the by-election had been: "A vote of confidence in the way Labour is changing," and "a wake-up call for David Cameron."
The Tories will probably attempt to claim that the seat was won on postal votes, many of which would have been cast before David Cameron's veto of an EU treaty a week ago. If everyone had voted this week, you can imagine them saying, the result might have been different.
Speaking to HuffPost UK before the polls closed, one Tory activist said they expected Labour to win: "I've seen a lot of UKIP posters, and I was a teller at different polling stations and no Labour person came, they think they have it firmly in the bag."
The campaign has felt fairly lacklustre for the two main parties - only the Tories or Labour can win here - with a visit to the constituency by HuffPost UK last weekend revealing a largely apathetic electorate.
The Tories have been trying to keep their spirits up during the campaign, despite polling data commissioned by Conservative peer Lord Ashcroft which suggested at one point Labour were leading by 22 points.
Ed Miliband has been campaigning in the seat in recent days, after some criticism of his apparent absence from any of the campaign literature in the first couple of weeks.
The by-election gives the The Labour leader a more cheerful end to what's been a fairly miserable week in the national media, with two opinion polls showing his party's support eroding - and another poll showing the Tories taking the lead.
It hasn't been helped by yet another uninspiring performance at PMQs on Wednesday and a general consensus that a majority of the public are backing the Tories' approach to both Europe and the economy.